There is a locking device for an auxiliary lock of U.S. Pat. No. 5,010,749, which comprises a rotatable ring and a base. The ring is fitted around the auxiliary lock and combined with the base. Then they are mounted in the door to let a large part of the rotating ring be exposed outside the door, and rotating the ring can cause the dead bolt of the auxiliary lock to extend out locking the door.
When the rotatable ring in said lock is rotated, it does not bump against anything, so a person who turns it may have a wrong feeling that the lock is not locked. So this invention has been devised to improve its structure which gives a user a feeling of bumping movement and clicking sounds when the rotatable ring is rotated so as to make it clear that this lock has been locked.